[PATCH 2/2] platform/x86/intel/pmc: Add PSON residency counter

[Michael Bottini <michael.a.bottini@xxxxxxxxxxxxxxx>]

Tiger Lake devices have the capability to track the duration
of time that their Power Supply Units (PSUs) are turned off during S0ix.
This patch adds a debugfs file `pson_residency_usec` to provide
access to this counter.

In order to determine whether the device is capable of PSON,
use acpi_init_properties() to reevaluate _DSD.

Signed-off-by: Michael Bottini <michael.a.bottini@xxxxxxxxxxxxxxx>
---
 drivers/platform/x86/intel/pmc/core.c | 46 +++++++++++++++++++++++++++
 drivers/platform/x86/intel/pmc/core.h |  7 ++++
 2 files changed, 53 insertions(+)

diff --git a/drivers/platform/x86/intel/pmc/core.c b/drivers/platform/x86/intel/pmc/core.c
index 7c4bf7d22fd5..6cf06aecf368 100644
--- a/drivers/platform/x86/intel/pmc/core.c
+++ b/drivers/platform/x86/intel/pmc/core.c
@@ -595,6 +595,8 @@ static const struct pmc_reg_map tgl_reg_map = {
 	.lpm_sts = tgl_lpm_maps,
 	.lpm_status_offset = TGL_LPM_STATUS_OFFSET,
 	.lpm_live_status_offset = TGL_LPM_LIVE_STATUS_OFFSET,
+	.pson_residency_offset = TGL_PSON_RESIDENCY_OFFSET,
+	.pson_residency_counter_step = TGL_PSON_RES_COUNTER_STEP,
 	.etr3_offset = ETR3_OFFSET,
 };
 
@@ -1084,6 +1086,20 @@ static int pmc_core_dev_state_get(void *data, u64 *val)
 
 DEFINE_DEBUGFS_ATTRIBUTE(pmc_core_dev_state, pmc_core_dev_state_get, NULL, "%llu\n");
 
+static int pmc_core_pson_residency_get(void *data, u64 *val)
+{
+	struct pmc_dev *pmcdev = data;
+	const struct pmc_reg_map *map = pmcdev->map;
+	u32 value;
+
+	value = pmc_core_reg_read(pmcdev, map->pson_residency_offset);
+	*val = (u64)value * pmcdev->map->pson_residency_counter_step;
+
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(pmc_core_pson_residency, pmc_core_pson_residency_get, NULL, "%llu\n");
+
 static int pmc_core_check_read_lock_bit(struct pmc_dev *pmcdev)
 {
 	u32 value;
@@ -1788,6 +1804,30 @@ static void pmc_core_get_low_power_modes(struct pmc_dev *pmcdev)
 	}
 }
 
+static bool pmc_core_is_pson_residency_enabled(struct pmc_dev *pmcdev)
+{
+	struct platform_device *pdev = pmcdev->pdev;
+	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
+	acpi_status status;
+	u8 val;
+
+	if (!adev)
+		return false;
+
+	acpi_init_properties(adev);
+	status = acpi_evaluate_object(adev->handle, "PSOP", NULL, NULL);
+
+	if (ACPI_FAILURE(status))
+		return false;
+
+	if (fwnode_property_read_u8(acpi_fwnode_handle(adev),
+				    "intel-cec-pson-switching-enabled-in-s0",
+				    &val))
+		return false;
+
+	return val == 1;
+}
+
 static void pmc_core_dbgfs_unregister(struct pmc_dev *pmcdev)
 {
 	debugfs_remove_recursive(pmcdev->dbgfs_dir);
@@ -1856,6 +1896,11 @@ static void pmc_core_dbgfs_register(struct pmc_dev *pmcdev)
 				    pmcdev->dbgfs_dir, pmcdev,
 				    &pmc_core_substate_req_regs_fops);
 	}
+
+	if (pmcdev->map->pson_residency_offset && pmc_core_is_pson_residency_enabled(pmcdev)) {
+		debugfs_create_file("pson_residency_usec", 0444,
+				    pmcdev->dbgfs_dir, pmcdev, &pmc_core_pson_residency);
+	}
 }
 
 static const struct x86_cpu_id intel_pmc_core_ids[] = {
@@ -1944,6 +1989,7 @@ static int pmc_core_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	platform_set_drvdata(pdev, pmcdev);
+	pmcdev->pdev = pdev;
 
 	cpu_id = x86_match_cpu(intel_pmc_core_ids);
 	if (!cpu_id)
diff --git a/drivers/platform/x86/intel/pmc/core.h b/drivers/platform/x86/intel/pmc/core.h
index 333e25981e8e..822d77f49861 100644
--- a/drivers/platform/x86/intel/pmc/core.h
+++ b/drivers/platform/x86/intel/pmc/core.h
@@ -214,6 +214,10 @@ enum ppfear_regs {
 #define TGL_LPM_PRI_OFFSET			0x1C7C
 #define TGL_LPM_NUM_MAPS			6
 
+/* Tigerlake PSON residency register */
+#define TGL_PSON_RESIDENCY_OFFSET		0x18f8
+#define TGL_PSON_RES_COUNTER_STEP		0x7A
+
 /* Extended Test Mode Register 3 (CNL and later) */
 #define ETR3_OFFSET				0x1048
 #define ETR3_CF9GR				BIT(20)
@@ -301,6 +305,8 @@ struct pmc_reg_map {
 	const u32 lpm_residency_offset;
 	const u32 lpm_status_offset;
 	const u32 lpm_live_status_offset;
+	const u32 pson_residency_offset;
+	const u32 pson_residency_counter_step;
 	const u32 etr3_offset;
 };
 
@@ -337,6 +343,7 @@ struct pmc_dev {
 	int num_lpm_modes;
 	int lpm_en_modes[LPM_MAX_NUM_MODES];
 	u32 *lpm_req_regs;
+	struct platform_device *pdev;
 };
 
 #define pmc_for_each_mode(i, mode, pmcdev)		\
-- 
2.25.1